Autumn leaf, Dew-covered

A leaf is an organ of a vascular plant and is the principal lateral appendage of the stem. The leaves and stem together form the shoot.Foliage is a mass noun that refers to leaves collectively.

Diagram of a simple leaf.
Apex Midvein (Primary vein) Secondary vein. Lamina. Leaf margin Petiole Bud Stem
Typically a leaf is a thin, dorsiventrally flattened organ, borne above ground and specialized for photosynthesis. In most leaves, the primary photosynthetic tissue, the (palisade mesophyll), is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus palisade mesophyll is present on both sides and the leaves are said to be isobilateral.